Oil Free Air Compressors: Best Choice for Pure Air
Two Stage Oil-Free Rotary Screw Compressors
Fixed and regulated speed rotary screw air compressors
The launch of this brand-new range of oil-free screw compressors offers the lowest total cost of ownership on the market, with up to 8% higher flow rates, up to 7% energy reduction and guaranteed air purity. These high output oil-free machines now cover a wide flow range from 14.6 to 28.3 m³/min. The DX90 to DX160 models are fixed speed and the DX90RS to DX160RS models are regulated speed.
Pressure range: 4 to 10.7 bar
Volume flow: Capacity of 6.7 to 28.3 m³/min
Motor power: 90 to 160 kW
CompAir has extended its proven range of DX, oil-free rotary screw air compressors with the launch of the new DX90-160 (RS) series, offering up to 14 per cent improvement in energy efficiency and up to eight per cent higher flow compared to industry standards. The range has been designed to offer best-in-class energy performance, excellent reliability and reduced lifecycle costs - in an oil-free compressor which is Class Zero certified according to ISO 8573-1:2010. This means there is virtually no risk of contamination in the production process, making it ideal for applications where high levels of air purity are essential. The new range includes fixed and variable-speed models from 90 to 160 kW.
David Bruchof, Oil-Free Product Manager, said: “Capable of delivering pressure ranges from 4 to 10.7 bar and volume flow between 6.7 to 28.3 m³/min, our new series is the latest enhancement to our proven range of two-stage, oil-free rotary compressors and has been designed to prioritise efficiency at every stage. From the completely redesigned air end to the unparalleled energy efficiency improvements of the whole compressor package, this new series will deliver substantial energy savings, with the lowest cost of ownership for rapid return on investment.”
Oil-free air compressors—especially two-stage oil-free rotary screw compressors—are widely considered the best choice when pure, contamination-free air is critical. Here’s a clear, practical breakdown of your topic along with real product examples.
🔷 Why Oil-Free Air Compressors Are the Best for Pure Air
Oil-free compressors compress air without any oil in the compression chamber, ensuring zero risk of contamination.
Key advantages:
✅ 100% clean air (ideal for pharma, food, electronics)
✅ No oil carryover → protects products & equipment
✅ Lower maintenance (no oil changes)
✅ Meets strict standards like Class 0 air purity
👉 These are essential in industries where even tiny oil traces are unacceptable (e.g., hospitals, semiconductor manufacturing).
🔷 Two-Stage Oil-Free Rotary Screw Compressors
These are advanced industrial compressors using two compression stages for higher efficiency and pressure.
How they work:
Air is compressed in Stage 1
Cooled (intercooler)
Compressed again in Stage 2 for higher pressure and efficiency
👉 Two-stage design is often required because oil-free systems need multiple stages to reach high pressure efficiently.
Benefits:
🔹 Higher efficiency & energy savings
🔹 Better cooling → longer lifespan
🔹 Suitable for continuous industrial use
🔹 Delivers high flow rates (up to ~25.9 m³/min in some models)
🔷 Fixed Speed vs Regulated (Variable Speed) Compressors
1. Fixed Speed Rotary Screw Compressors
Runs at constant speed
Best for steady air demand
✔ Simple & cost-effective
❌ Wastes energy during low demand
2. Regulated Speed (Variable Speed Drive – VSD)
Adjusts motor speed based on demand
✔ Energy savings (up to ~30–35%)
✔ Stable pressure output
✔ Ideal for fluctuating workloads
🧠 Final Takeaways
Choose two-stage oil-free if you need high pressure + maximum purity + efficiency
Choose VSD (regulated speed) if your air demand fluctuates
Choose fixed speed if your load is constant and predictable
